A VOIDING RADON EXPOSURE

Although radon exposures of the public are regularly hundreds and even thousands of times higher than from nuclear power operations, that alone may not be cause for alarm. Our purpose here is not to scare readers with the dangers of radon, but to point out the inconsistency of the media and of the politicians bent on pleasing them.

There are, however, cases when exposure may be high, mainly in insufficiently ventilated rooms. One to two air changes per hour (of the volume of the room lived or slept in) are considered safe, but this runs counter to energy conservation, since ventilation expels both the air and its heat (or air-conditioned coolness in the summer).

The easiest cure is compromise: Insulation should stop conduction of heat through the walls (the main cause of leakage), but should not prevent a little heat loss by convection through ventilating openings. But then, "a little" loss on a calm day may be severe when it is windy. On the other hand, "tight" houses, e.g. houses lined with plastic (polyethylene) "vapor barriers," are dangerous. They receive headlines about super-savings, but not a footnote about lung cancer. Fortunately, the human nose will usually alert the energy saver: radon is odorless, but the gases trapped simultaneously are not.

An air-to-air heat exchanger will extract heat (or coolness, in the summer) from the stale air being expelled, allowing the user to change the air, yet retain some of its heat (about 60 to 70%). However, such heat exchangers are neither simple nor cheap. They use electric power (40 to 500 W), are liable to malfunction, and cost $500 to $1,000 (150 cfm) -- S43,000 for a large building (7,000 cfm) -- plus freight and installation.

The real cure is abundant energy. Unfettered by either price controls or witch hunts, energy can be made abundant enough so people do not have to choose between dollar cost and cancer.

[More.R. James: "A solution for indoor pollution," Mechanics Illustrated, Oct 1981 (principles); W.A. Shurcliff, "Air-to-air heat exchangers for houses," Solar Age, March 1982 (table of 16 types with performance and cost); price lists and booklets (such as Mitsubishi "Lossnay") from local heating and air-conditioning companies.]